ENCePP Guide on Methodological Standards in Pharmacoepidemiology

5.3.1. New-user designs

New user (incident user) designs
can avoid prevalence bias by restricting the analysis to persons under
observation at the start of the current course of treatment, therefore with the
same baseline risk. Evaluating medication effects outside of clinical trials: new-user
designs (Am J Epidemiol 2003;158 (9):915–20). In addition to
defining new-user designs, the article explains how they can be implemented as
case-control studies and describes the logistical and sample size limitations
involved.